A Partial Linearization Method for Multi-Objective Continuous Network Design Problem with Environmental Considerations

Nowadays, the environmental impact of transportation project and, especially air pollution impacts, are major concerns in evaluating transportation projects. Based on this concern, beside definition of traditional objective functions like total travel time and total investment cost, different type of environmental related function is considered as objective function in urban network design. In this paper, the continuous network design problem (CNDP) is formulated as a multi-objective bi-level optimization problem. The objective function of the upper level problem is a weighted combination of total travel time, total investment cost and total vehicular emission in the network. The lower level problem is the traffic assignment problem which would predict the vehicular flow on each link in the network. A new solution algorithm is proposed for solving the bi-level optimization problem by the partial linearization of the lower level problem. The solution algorithm was applied to the city of Sioux Falls, a well known transportation network.